Audio speakers or loudspeakers are ubiquitous on many devices used by individuals, including televisions, stereo systems, computers, smart phones, and many other consumer devices. Generally speaking, an audio speaker is an electroacoustic transducer that produces sound in response to an electrical audio signal input.
Given its nature as a mechanical device, an audio speaker may be subject to damage caused by operation of the speaker, including overheating and/or overexcursion, in which physical components of the speaker are displaced too far a distance from a resting position. To prevent such damage from happening, speaker systems often include control systems capable of controlling audio gain, audio bandwidth, and/or other components of an audio signal to be communicated to an audio speaker.
Such control systems operate based on various measured characteristics of a speaker system. For example, a control system may sense a current and voltage associated with a loudspeaker and based thereon, determine an electrical impedance or an electrical admittance of the speaker. Such electrical impedance or an electrical admittance, as well as one or more other mechanical or electrical parameters associated with the speaker system, may then be processed to determine or estimate a displacement of a speaker, and control the speaker system such that the displacement does not exceed a maximum displacement in which damage to the speaker may occur.
Existing speaker protection control systems often employ a “causal architecture” between measured voltage and measured current, thus permitting only the capture by the control system of causal characteristics of the relationship between the measured current and the measured voltage. Accordingly, such an architecture is incapable of capturing non-causal portions of electrical admittance or impedance responses, and thus can lead to electrical system identification inaccuracies, limited working frequency ranges, and/or other disadvantages.